WASHINGTON -- Pope Benedict XVI met Thursday for the first time with US victims abused by priests, offering them his support after he acknowledged the pain and damage caused by the Church's sex scandal.

After celebrating Mass with a crowd of some 48,000 people, the pope held unprecedented talks with a small group of people who were sexually abused by members of the clergy, the Vatican said in a statement.

The group prayed together and the pontiff then listened to the stories of the victims, and "offered them words of encouragement and hope."

"His Holiness assured them of his prayers for their intentions, for their families and for all victims of sexual abuse," the statement added.

The private meeting with five victims lasted 20 to 25 minutes, officials said.

Some of the victims told CNN that Benedict had given them hope that the Church would change.

"I said to him, Holy Father, you have a cancer growing in your flock and you need to do something about that, and I hope you understand me and hear me," Bernie McDaid, who was abused at the age of 12, told the network.

"And I touched his heart, and he nodded again. He looked down at the floor and looked back up, and nodded," he said.

Said another victim, Olan Horne: "When you meet somebody and you know that you don't have to convince them that there's a problem, and they intrinsically understand their role in it, you know it."

"And we could see that. We could see it in the eyes, we could see it in the sincerity and there's a phenomenal hope that I came out of that meeting with."

The pope was accompanied by the archbishop of Boston, Cardinal Sean O'Malley, who was given a list of 1,000 victims in the diocese -- where the massive scandal was first reported.

The pope has already apologized several times since the start of his first US papal visit saying he was "deeply ashamed" of the scandal which has rocked the Catholic Church.

A US group for victims of clerical sexual abuse said the meeting was positive but that the pope needed to do much more to reform the Church and prevent further abuse.

"This is a small, long overdue step forward on a very long road," the Survivors Network of those Abused by Priests (SNAP) said in a statement.

The US clergy sex scandal mushroomed into a nationwide embarrassment for the Church after the then archbishop of Boston, Cardinal Bernard Law, resigned in 2002 amid intense pressure due to his handling of abusive priests.

Last year, the US Church paid out $615 million (400 million euros) to settle sex abuse cases, according to the US Conference of Catholic Bishops.

"No words of mine could describe the pain and harm inflicted by such abuse," Benedict told some 48,000 people who gathered for a Mass earlier Thursday in the new Washington Nationals ballpark celebrated by the pontiff.

The Church was making amends though, Benedict insisted, in dealing "honestly and fairly with this tragic situation and to ensure that children ... can grow up in a safe environment."

The crowds of faithful had given the pope a joyful welcome as he appealed for Americans to embrace the church and help it heal from its tragic recent past.

But the tone turned somber when the pope in his homily once again addressed the "tragic" sexual abuse of children by priests which has become a dominant theme of his six-day visit to the United States.

The crowd sat silent, some fanning themselves in the bright spring sunshine, as Benedict urged Catholics in the United States and around the world to reinforce their own faith and seek new converts in responding to "signs of alienation, anger and polarization" in society at large.

"The challenges confronting us require a comprehensive and sound instruction in the truths of the faith," he said, decrying rising violence, looser morals, "and a growing forgetfulness of God."

Bishops, priests, seminary students, ordinary Americans of all races and families with children in tow had flocked to the stadium to hear the German-born pontiff.

The service was punctuated by hymns sung by four choirs of 570 singers, with renowned tenor Placido Domingo and soprano Denyce Graves singing solos.

On Friday, the pope travels to New York where he is expected to address the UN General Assembly, which the Vatican said will be the highlight of his US visit.

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